Zinc oxide films prepared

by sol-gel spin coating

指導老師：林克默 學 生：吳仕賢 報告日期： 2010.01.15

Y. Natsume, H. Sakata, Thin Solid Films 372 (2000) 30.Department of Applied Chemistry, School of Engineering, Tokai University, 1117, Kitakaname, Hiratsuka, Kanagawa, 259-1292, Japan.

大綱前言實驗流程結果與討論結論

前言 ZnO films are n-type wide-gap semiconductors with optical

transparency in the visible range. Zinc oxide films deposited by chemical spray pyrolysis had

resistivities (~10-3 Ωcm). Al-doped ZnO films formed by sol-gel dip coating gave

resistivities of (7-10) × 10-4 Ωcm. No reports are found on zinc oxide films prepared by sol-gel

spin-coating that can be made with a simple coating apparatus.

實驗流程

結果與討論

The (002) peak intensity increased with an increase in the annealing temperature. However, the full width at half-max-ima (FWHM) of the (002) peaks was hardly changed with increasing film annealing temperature. Hence, the multiple-coating or piling up of each ZnO film was considered not to disturb the overall growth of the films with c-axis orientation.

We confirmed that this shoulder peak was thought to be due to metallic zinc present, as interstitial atoms, in the lattice of ZnO crystallites in the film, rather than reduced Zn by Ar+ sputter-etching, because the shoulder peak existed from the outermost surface.

However, the resistivity increased mildly because the decrease of the carrier concentration might be controlled because of decreasing defects that produce donor levels, as a result, decomposition and oxidation of the precursor films became more active, and a better stoichiometry of the ZnO films was formed above 525 , ℃rather than the change of the mobility with the annealing temperature.

where Ea1 is the activation energy for band conduction as defined in Eq. 3., Ea2 , the activation energy for nearest neighbor hopping conduction, k, the Boltzmann constant and σ1 and σ2, the pre-exponential factors,espectively.

結論 The160-230nm thick films formed on Pyrex glass substrate were

polycrystalline with c-axis orientation. A minimum d.c. resistivity of 28.2 Ωcm was obtained by a 10-

cycle spin-coating of zinc acetate film followed by annealing in air at a temperature of 525 .℃

Grain boundary scattering was caused by thermionic emission of electrons over grain boundaries.

The optical band gap energy was obtained to be Eopt =3.2-3.21 ev for the films.